Semiautomatic telephone system



J. WICKS.

SEMIAUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAR. 4. 1918.

1,404,416. Patented Jan. 24, 1922 2 SHEETS-SHEET I.

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SEMIAUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAR-4,1918.

Patented Jan. 24, 1922'.

2 SHEETS-SHEET 2.

I nil 8\ h p Z HI 1 2 UNITED STATES JOHN WICIS, OI CHICAGO, ILLINOIS ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY,

01' CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SEMIAUTOIATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

HEISSUED Patented Jan. 24, 1922.

Application filed larch 4, 1918. Serial No. 220,151.

To all whom it may concern.

Be it known that I, J OHN WIOKS, a citizen of the United States of America, and a resident of Chicago, Cook County, and State of Illinois, have invented certain new and useful .Im rovements in semiautomatic Telephone ystems, of which the following is a specification.

My invention relates in general to improved circuits and apparatus for use in a semi-automatic telephone system in which automatic switches are controlled either automatically by a subscriber or through the medium of an operator to establish connections.

More specifically, my invention relates to means whereby in such a system, when a call is made from a subscriber, the called substation will be signaled as in the usual practice; but, when a call is extended throu h the medium of an operator, the called su scriber will first be signaled automatically,

and then the operator may re-ring the called subscriber by the use of her ringing key.

In a system of this character, it is often desired to enable the operator to re-ring the called subscriber after the automatic ring has been disconnected, either because the called subscriber has hung up his receiver before the conversation was completed or because the operator has another call waiting for the same line.

The object of my invention, therefore, is to provide an improved switching mechanism for connecting with a called line, which mechanism may be used either by a subscriber or an operator and in which meansv are provided for enabling the operator to re-ring the called subscriber.

In the drawings, I have shown an operators toll selector E (Fig. 1) having access to a connector switch H (Fig. 2) which in turn has access to subscribers lines. This connector H is also multipled in the banks of local selectorswhich are used when a subscriber in the same exchange desires to use the connectorv H.

The cord circuit C of which only a portion of the local end is shown, may be of any approved long distance type and comprises amongother essentials the usual tip and ring talking strands terminating in the plug P, and a ringing key K. The-calling device CD may be of any well known two wire type such for example as the one shown in British patent to Dicker N 0. 29,654 of 1910.

have shown the switches in operated osition, that 1s, in the position assumed a er the call has been set up from an operator and after the called subscriber has answered, to d sconnect the automatic ringing circuit. To ring the called subscriber again after he has hung up his receiver is accomplished by means of the differentially wound relay 42 in the connector H and a specially tuned relay 122 in the selector E. The relay 42 1t Wlll be noted, is short-circuited durin the conversation to remove its resistance rom the talking circuit and is also left out of the circuit when the connector H is used in a local call.

I will now point out more in detail, referring to the accompanying drawings, the method of operation involved when an operator establishes a connection with the substation A (Fi 2) automatically rings the same first an may thereafter re-I'ing the substation A by means of the improved circults.

The operator first inserts the calling lug P of her cord circuit into the jack X of the selector E thereby closing at the springs 2, a circuit for line relay 5 which may be traced from ground at the calling device sleeve of plug P and jack X, springs two, springs 3 and 4:, and rela 5 to battery. The relay 5 will immediatel y energize over this circuit and close a circuit for the slow relay 6 from ground through springs 8 and 9, and relay 6 to battery. The relay 5 also closes a high resistance shunt about the condenser 10 which is connected between a pair of the windings of the repeating coil, said circuit extending from the upper side of condenser 10, springs 11, lower winding of relay 12, and resistance 13 to the lower side of the condenser. The closure of this shunt circuit, however, has no effect at this time as the talking circuit is still open at the springs 14 and 15. The energization of the slow relay 6 over the previously traced circuit supplied a ground to the supervisory circuit to light the busy lamp 16, and others which may be multipled therewith, through springs 19 and 20; grounds the upper winding of the electropolarized relay 12, which relay, however,'is arranged so that it will not operate its armatures unless the current flowing in both windings is in the same direction, and also repares a circuit from the back contact 0 relay 5 through the series slow relay 16 and the vertical magnet 17 at the springs 18.

Now when the operators calling device is operated for the first digit of the called number, the circuit of the line relay 5 is thereby interrupted a corresponding number of times. Each time the relay 5 deenergizes it closes a circuit from ground through springs 8 and 21, relay 16, and vertical magnet 17 to battery. The vertical magnet 17 operates in response to this series of im ulses to 11ft the wipers 22, 23 and 24 opposite some level of the banks to which connector switches,

having access to a desired group of lines, are

connected. Although the circuits of relays 6 .and 16 are interrupted momentarily at each operation of relay 5 both will remain energized during transmission of such impulses and after the impulses cease and relay 5 comes to rest energized, the relay 16 will fall back and relay 6 will remain energized. As soon as the vertical magnet operates the shaft and wipers one step, the off-normal springs 25 and 26 close. The springs 26 close the circuit of release magnet 27 at one point and the springs 25 close a point in the circuit of the rotary interrupter relay 28. The circuit of the release magnet 27 is maintained open at the back contact of relay 6. The relay 28, however, energizes as soon as the springs 25 close over a circuit extending from ground through springs 19 and 20 of relay 6, springs 29 and 30 of relay 16, springs 25, and relay 28 to battery. The relay 28, upon energizing, closes a locking circuit for itself at the springs 31 extending from ground through springs 31, interrupter springs 32 of rotary magnet 33, springs 25, and relay 28 to battery, and also closes one point in the circuit of the rotary magnet 33 at sprin 34. Now after the impulses for the first digit cease and the relay 16 deenergizes, a circuit is closed for the rotary magnet extending from ground through springs 19 and 20, springs 29 and 35, springs 34, and magnet 33 to battery. The rotary magnet 33, therefore, operates to step the wipers 22, 23 and 24 one step onto the first set of contacts in the bank level before which it stands. Another result of the operation of the rotary magnet is to open the locking circuit of the relay 28 at springs 32. The relay 28 will therefore deenergize and open the circuit of the rotary magnet at springs 34 and also open a contact in its own locking circuit at springs 31. As soon as the springs 34 open, the rotary magnet will deenergize and again close springs 32. Assuming now that the trunk line selected is busy, then a ground potential'will be found on the private contact with which the wiper 24 is now in contact. As soon, therefore, as the springs 32 come into contact a new circuit will be closed for the relay 28 extending from ground over the wiper 24, springs 36 and 37, sprin s 32, springs 25, and relay 28 to battery. T e relay 28 will again operate to close the circuit of magnet 33 and its own circuitto step the wipers to the next contact. This alternate operationof the relay 28 and rotary magnet 33 continues unti reached, at which time no ground will be found uponthe private contact and the relay 28 will therefore remain deenergized after the springs 32 are.closed. It may be here noted that, durin the energization of the relay 16 and also d uring the rotation of the wipers, the relay 38, although in series with the relay 28, is maintained short circuited, first by the ground through springs 19, 20, 29 and 30 and during rotation by the ground on the private wiper. The last mentioned short circuit extends from ground on wiper 24, springs 36 and 37 relay 38, springs 20 and 19 to ground. Now, however, when an idle trunk is reached, this short circuit is removed and the relay 38 which is of high resistance energizes in series with relay 28. The circuit for energizing this relay extends from ground through the springs 19 and 20, relay 38, springs 32, springs 25, and relay 28 to battery. The relay 28 does not energize over this circuit on account of the high resistance of the winding of relay 38. The relay 38, upon energizing, extends the talking circuit from the windings 39 and 40 of the repeating coil to the wipers 22 and 23, and also prepares a lockin circuit for itself through the springs 36 an 41 which will be supplied with ground from the switch ahead as will be pointed out. Another result of the ener ization of relay 38 is to open the springs thereby preventing any further operation of the operating magnets.

Now as soon as the relay 38 closes its sprin s 14 and 15, a circuit is thereby establis ed for the line relay 41 of the connector H through the windings of the difi'erentially wound relay 42. The relay 42 does not energize at this time as its two windings oppose each other. The circuit for relays 41 and 42 extends from battery through the upper winding of relay 41, springs 43 and 44, upper winding of relay 42, wiper 22, springs 14, winding 39 of the repeating coil, springs 11, lower winding of relay 12, resistance 13, which may be approximatel 200 ohms, winding 40 of repeating coi springs 15, wiper 23, lower winding of relay 42, springs 45 and 46, and lower winding of relay 41 to ground. The relay 12 of. selector E does not energize at this time as the current in its two windin s flows in opposite directions. The line re ay 41, upon energizing, closes the circuit of slow relay 52 through thesprings 53 and 54, which relay, upon energizing, connects ground to the rean idle trunk line 1slease trunk through springs 47, 122 and 121, to render the switch busyto other calls and also to supply an additional ground to the holding circuit of relay 38 (Fig. 1).

Now when the operator sends out the second digit of the called number, the line relay 5 of selector E will be operated as is the previous digit to attract and detract its armatures a predetermined number of times. The closure of sprin s 8 and 21 has no effect at this time due to t e springs 7 being held open by relay 38. The opening and closing of springs 11, however, opens and closes the circuit, previously traced of the line rela 41 of the connector H. The relay 41, eac time it detracts its armature, operates to olpen and close the springs 53 and 62, to t ereby open and close a circuit for the vertical magnet. The circuit of the vertical magnet extends from ground through springs 53 and 62, springs 56 and 57 springs 63 and 64, slow relay 69, and vertical magnet to battery. The vertical magnet will be operated a number of times to step the wipers 71, 72 and 73 to a group or level of trunk lines in which the terminals of the desired line are located. Upon the first vertical step of the wipers, the off-normal springs 63 and 64 are opened and spring 63 comes into contact with spring 74, and the springs 75 are closed. Although the circuit for the vertical magnet is opened by the springs 63 and 64, a new circuit has been closed in the meanwhile by the operation of relay 69, which circuit extends from ground through springs 53 and 62, springs 56 and 57 springs 63 and 74, springs 76 and 77, and over the previously traced circuit through the vertical magnet. It may be noted that the slow relay 52 remains energized during the entire operation of the line relay regardless of the momentary deenergization thereof, and that the relay 69 remains enerized constantly during the first series of lmpulses, but deenergizes at the end of the first series when the line relay comes to rest energized. Now, when the relay 41 comes to rest energized after the impulses to the vertical'magnet cease, the relay 69 will deenergize, opening its own circuit at the springs 76 and 77 and closing at the springs 76 and 78, a point in the circuit of the rotar magnet 79 and also of the slow relay 80. ow, when the line relay 41 is again operated in response to the third or last digit, through the medium of the line relay 5 of selector E, the rotary magnet 79 is operated to rotate the wipers 71, 72 and 73 to the terminals of the desired line. The circuit of the rotary magnet extends from ground through springs 53 and 62, springs 56 and 57, springs 63 and 74, springs 76 and 78, springs 81, springs 82 and 83, and rotary magnet 79 to battery. A branch of this circuit extends from the springs 81 through the slow relay 80 to battery so that relay 80 and magnet 79 are energized in multi le. The relay 80 energ izes upon the first impulse and closes the spr ngs 84, thereby short circuitiug the springs 81 of relay 85 and maintaining the circuit of itself and magnet 79 closed irrespective of the condition of relay 85 during this series of impulses. Another result of the energization of the slow relay 80 is to close a point in the circuit of the busy or test relay 85, at the springs 86 and 87. The relay 80 being slow acting, will maintain the springs 86 and 87 closed for a brief interval "after the line relay has come to rest and connection has peen made with the terminals of the desired Assuming the called line to be busy because of some call being extended therefrom, as shown, then the private contact will be grounded. Before the springs 86 and 87 are opened, therefore, a circuit will be completed for the busy relay 85, extending fromground to the wiper 73, springs 86 and 87, springs 65, and relay 85 to battery. The relay 85 energizes to close a look ing circuit for itself which is closed as soon as relay 80 falls backand extends through springs 65, springs 87 and 99, springs 96 and 91, springs 90 and 89, and springs 121, 120 and 47 to ground; opens the circuit of the relay 88 at springs 92 and 91; opens the initial energizing circuit for the rotary magnet and relay 80 at springs 81; closes a shunt or short circuit about the lower winding of relay 42 at springs 97, and connects the secondary winding of the busy machine M with the lower talking conductor, thereby giving the operator a busy signal.

The short circuit which was thus established about the lower winding of relay 42 causes said relay, whose windings are differential, to be energized, thereby switching the locking circuit of the busy relay 85 to the wiper 73, this new circuit extends from ground at wiper 73, springs 98 and 90, springs 91 and 96, springs 99 and 87, springs 65, and relay 85 to battery. It will be seen therefore, that the relay 85 instead of being permanently locked, remains energized only 116 as long as the called line is in use and until the ground is removed from the private contact thereof.

As soon therefore as the ground disappears from the private wiper 73, the relay 120 85 will deenergize and restore its springs to normal. The shunt being removed from the winding of rela 42 by the openin of springs 97 said relay will deenergize a ter a brief interval and .close one point in the cir- 126 cuit of rela 88. The circuit for relay 88 is now comp etc and extends from ground through springs 47, 122 and 121, springs 89 and 90, springs 91 and 92, lower winding of relay 88, springs 90 and 86, private wiper 130 busy and also to short circuit its own lower winding. Another result of the energization of relay 88 is the closure of the springs 102 and 103, thereby connecting ringing current to the called line. The ringing circuit extends from battery through the upper winding of relay 48, springs 104 and 105,

springs 102, wiper 71, to and through the ringer of substation A, and back through wiper 72, springs 103, springs 106 and 107, to spring 108. The spring 108 is controlled by the common interrupter relay 109 to connect the above traced ringing circuit alternately to the battery B and to the generator B.

As long as the receiver of the called station remains on the hook, the ringer thereat will be operated alternately and the relay 48 will remain deenergized, being nonresponsive to alternating current. When the receiver is removed in response to the signal, a direct current circuit will be established for said relay 48 which will immediately energize to disconnect the ringing lead from spring 108 from the circuit of the called line by opening the springs 107 and 106 and to connect the talking circuit from the condensers 110 and 111 to the wipers 71 and 72. The energization of relay 48 connects the ground from springs 112 through springs 113 to close a locking circuit for its own lower winding and also connects said ground to lower winding of back bridge relay 114. The springs 105 and 106, upon engaging their front contacts, close a circuit for the back bridge relay 114 extending from ground at relay 52, through springs 112, springs 113, lower winding of relay 114, front contact of spring 106, springs 103, wiper 72, through the talking equipment of substation A, and back throu h wiper 71, springs 102, spring 105 and its ront contact, and upper winding of relay 114 to battery. The relay 114 energizes over this circuit and operates the springs 115 and 116 and the associated contacts to reverse the connections of line rela 41 to the talking circuit, and to short circuit the windings of relay 42. This causes a reversal of current in the talking circuit to the lower winding of the back bridge relay 12 of the selector E. The relay 12 now having both windings assisting each other operates to close the circuit of relay 120 at springs 121. The relay 120, upon energizing, opens the circuit of relay 122 at springs 123, closes a new circuit for the lower winding of relay 12 at springs 124, and replaces the relay 6 directly in the operating clreuit of the operator in lace of relay 5 which now deenergizes. he closure of springs 125' at this time close the circuit for a supervisory relay in the operators cord circuit to control the usual operators signal in order to notify the operator that the called man has answered and alsoshort circuits the rela 122. The springs 117 by the relay 114 (Fig. 2) are also closed to maintain the connector relay 88 energized in case the o erator should disconnect the calling plug from the jack X before the called party has hung up, and thereby maintaining the connector in operated position, also the springs 118 are opened to maintain the circuit of release magnet 119 open until the called man hangs up.

Conversation may now proceed over the heavy conductors shown in the drawing and when the conversation is completed, the connector may be released by either the operator or called man, that is, by the last party to restore his receiver, while the selector E is restored by the operater only. Should the calling subscriber hang up first, the operator will then remove the plug from the jack X and thereby 0 en the circuit of the relay 6 at the jack. The relay 6, upon deenergizing, closes an energizing circuit for the release magnet 27 and opens the holding circuits of relays 38 and 12. The selector E is thereupon released and in releasing opens the circuit of line relay 41 of connector The relay 41, upon deener izing, opens the circuit of relay 52. The eenergization of these two relays prepares a circuit for the release magnet 119 which is held open at springs 118 of back bridge relay 114. Now, therefore, as soon as the called subscriber hangs up his receiver, the switch will be re leased in the usual manner b the deenergi zation of relay 114 and the su se uent operation of release magnet 119. hould the called subscriber have hung u his receiver first then the relay 114 would deenergize to close the springs 118 and to again operate the supervisory signal in the operators cord circuit by means of relays 12 and 120 of selector E, after which the operator would withdraw the plug to deenergize relay 41 and release the switches in the usual manner.

When the operator is callin a subscriber in the manner pointed out, it is often necessary for the operator to re-ring the called subscriber either because the called subscriber hangs up too soon or because the operator has another call waiting for the same subscriber. In this case, the operator will actuate the ringin key K to connect generator out over cor circuit and through the windings of a specially tuned relay 122' (Fig. 1). The relay 122 will not be short circuited by the springs 125 at this time, as relay 120 will be deenergized when the called subscriber hangs up. The relay 122, upon energizing, closes the springs 126 to short circuit one windin of the relays 42 and 41 (Fig. 2). This s ort circuit extends from ground through springs 126, winding 40 of the repeatin coil, springs 15, wiper 23, lower winding 0 relay 42, springs 45 and 46, and lower winding of re ay 41 to ground. The relay 42 being differential will energize at this time to open the springs 112, which springs control the ground connection to ring cut-off relay 48 as before pointed out. The relay 48 will therefore deenergize to again c ose the previously traced ringing circuit for the called station, after which, the relays are operated in the usual manner when the call is answered to disconnect the ringing circuit and again converse over the talking circuit shown.

It will be seen therefore that I have provided a very useful and eflicient method by which the called subscriber may be re-rung or signaled by an operator, after the usual automatic ringing current has been disconnected and the called subscriber has again restored her receiver, and that this method is very simple and comprises only a means for again starting the automatic ring which may then be cut ofi' by the response of the called man.

Having fully described and ascertained my invention in the foregoing specification, what I claim to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a called line, means for establishing a connection with said called line, a source of signaling current, means for automatically connecting said source of current to the called line means for interrupting said current to intermittently operate a signal thereat means for disconnecting said current, a source of alternating current, and means for applying said alternating current to said connection to actuate, means for again applying said ringing current to the called line to operate the signal before said connection is released.

2. In a telephone system, a called line, means for establishing a connection with said called line and means controlled by the called subscriber for releasing said connection, a source of signaling current, means for automatically connecting said source of current to the called line to operate a signal thereat and for disconnecting said current and manual meansfor again applying said ringing current to the called line to 0 rate the signal before said connection is re eased.

3. n a telephone system, an automatic switch for establishing a connection to 0. called line and for automatically applyin signaling current thereto, means controlled by the called subscriber for releasing said connection, means in said switch for disconnecting said signaling current from the called line, and means for a ain causing said current to be applied to said line to signal the subscriber on said line a second time.

4. In a telephone system, an automatic switch for establishing a connection with :1 called line and for applying signaling current thereto to signal a subscriber on said line, means for automatically disconnecting said current when the subscriber responds to said signal, means controlled by the called subscriber for rele asin the connection, and means for again app ying said current to the called line without operating said releasing means after said current has been disconnected by the called subscriber.

5. In a telephone system, a pair of subscribers lines, means for establishing a connection between said lines, and for automatically applying signaling current to the called one of said lines to signal the subscriber thereon, means controlled by the called subscriber for disconnecting said current from his line and for releasing said connection, means for preventing the called subscriber from releasing said connection, and means for again applying signaling current to the called line when the called subscriber hangs up first and before the connection has been released.

6. In a telephone system, a called line, means for establishing a connection with said line and for automatically applying signaling current thereto, a relay, an energizing circuit for said relay including said called line, means controlled by the called subscriber for closing said energizing circuit to operate said relay to disconnect said signaling current, a circuit for locking said relay energized independent of the called subscribers control, and means for opening said locking circuit to permit said current to a ain be applied to said line.

7. n a telephone system, means for establishing a connection with a called line and for applying signaling current thereto, a relay for disconnecting said current from the called line, a circuit for locking said relay energized, a differential relay having contacts in series with said locking circuit, means for energizing said differential relay to open said locking circuit and again apply signaling current to said line.

8. In a telephone system, means for establishing a connection with a called line and for ap lying signaling current thereto, a relay or disconnecting said current from the called line, a circuit for locking said relay energized, a differential relay for controlling said locking circuit, a tuned relay for controlling said differential relay, and means for energizing said tuned relay to energize said differential relay to in turn open said locking circuit to cause sald signaling current to be again applied to said line.

9. In a telephone system, means for establishing a connection with 9, called line and for applying signaling current thereto, a relay for disconnecting said current from the called line, a circuit for locking said relay energized, a differential relay having contacts in series with said locking circuit, means for energizing said differential relay to open said locking circuit and again a ply signaling current to said line before the established connection for said called line is released.

10. In a telephone system, means for establishing a connection with a called line and for applying signaling current thereto, a rela for disconnecting said current from the ca led line, a circuit for locking said relay energized, a differential relay for controlling said locking circuit, a tuned relay for controlling said differential relay, and means for energizing said tuned relay to energize said differential relay to in turn open said locking circuit to cause said signaling current to be again applied to said line before the established connection with said called line is released.

11. In a telephone system, an operators position, a subscribers line, means controlled by the operator for establishing a connection with said line and for automatically applying ringing current thereto, a relay for automatlcally disconnecting said ringing current from the called line, a circuit for looking said relay energized, a differential relay for controlling said locking circuit a tuned relay for controlling said differential relay, and means controlled by the operator for so plying alternating current to said tuned re ay to energize the same, to thereby enerize said differential relay to open said lockmg circuit .and cause ringin current to again be applied to the subscri ers line.

12. In a telephone system, an operators position, a subscribers line, means controlled by the operator for establishing a connection with said line and for automatically applying ringing current thereto, a relay for automatically disconnecting said ringing current from the called line, a circuit for locking said relay energized, a diferential relay for controlling said locking circuit, a tuned relay for controlling said differential relay, and means controlled by the operator for supplying alternating current to said tuned relay to ener ize the same, to thereby energize said di erential relay to open said locking circuit and cause ringin current to again be applied to the subscribers line before the connection to the subscribers line is released.

13. In .a telephone system, an operators position, a subscribers line, means controlled by the operator for establishing a connection with said line'and for automatically applying rin ing current thereto, a relay for automatica 1y disconnecting said ringing current from the called line, a circuit for locking said rela energized, a double wound rela for contro ling said locking circuit, a relay for controlling said double Wound relay, and means controlled by the operator for energizing said last mentioned rela to energize said double wound relay by s ort circuiting one of its windings whereby the locking circuit of said first relay is opened and ringing current is again applied to the subscribers line.

14. In a telephone system, an operators osition a source of si nalin current means controlled by operator for establishing a connection to a called line and for automatically applying said signalling current thereto, said current being automatically cut off by the response of the called subscriber, a relay, a source of alternating current, means for preventing the release of the connection upon the subsequent hanging up of the receiver at the called station and for preventing said signalling current from being again applied to the called line upon the said restoration of the called subscribers receiver, and means controlled by the operator for applying said alternating current to said connection to actuate means for again applying said first current to said called line before the connection is relased.

15. In a telephone system, a called line, means for establishing a connection with said line, two sources of alternating current, a relay, means for automatically connecting one of said sources of current to said called line to operate a signal thereat, means for disconnecting said current, and means for applying said second source of current to said re ay to again apply said first mentioned ringin current to said called line.

16. n a telephone system, an operators position, a called line, means for establishing a connection with said line, two sources of alternating current, a relay, means for automatically connecting one of said sources of current to said called line to operate a signal thereat, means for disconnecting said current, and means under the control of the operator for aplying said second source of current to said relay to again apply said first inentioned ringing current to said called 17. In a telephonesystem, a telephone line, means for establishing a connection with said line, a source of signalling current,

means for automatically connecting said source of current to sai line to operate a signal thereat, means for disconnecting said source upon the response of the subscriber on said line, a source of alternating current, and means for applying said alternating current to said connection to again actuate said means for connecting said source of'signalling current to said line.

18. Ina telephone system, a telephone line, an automatic switch for establishing connection with said line, a source of signalling current, means in said switch for automatically connecting said source of current to said line,- means actuated by the response of the subscriber on the said line for disconnecting said source of ringing current, a source of alternating. current, and means for connecting said alternating current to said connection to actuate automatic means for again connecting said source of ringing current to said line.

19. In a telephone system, an operators position, an automatic switch, telephone lines accessible to said switch, means controlled by the operator at said position for operating said switch into connection with one of said lines, a source of ringing current, means in said switch for connecting said source of ringing current to said line,

automatic means operated upon the response of the subscriber on the connected line for disconnecting said ringing current, a source of alternating current, and means for connecting said source of alternating current to said connection to cause said source of ringing current to be again connected to the connected telephone line.

20. In a telephone system, an operators position, an automatic switch, telephone lines matic means in said switch operated upon the response of the subscriber on the connected line for disconnecting said ringing current, a source of alternating current and .a key at said operators position for connecting said source of alternating current to said connection to cause said source of ringing current to be again connected to the said connected line.

21. In a telephone system, a called line, means for establishing a connection with said line, a source of signalling current, means for automatically connecting said source of current to said called line to operate a signal thereat, means for disconnecting said current, a source of alternating current, and means for connecting said source of alternating current to said connection to again .apply said ringing current to said line.

22. In a telephone system, a called line, means for establishing a connection with said line, a source of signalling current, a relay, means for automatically connecting said source of current to said called line to operate a signal thereat, means for disconnecting said current, a source of alternating current, and means for applying said source of alternating current to said relay to again apply said signalling current to said called line.

Signed by me at Chicago, Cook County, Illinois, this 26th day of February, 1918.

JOHN WICKS. 

